pemission error with linked server

I've set up the linked server using the SQL script provided here and when I click on the Test button it works, but when I run a query or try to browse the Tables/View, I get some variation of:

The OLE DB provider "PGNP" for linked server "SHADOWDB" reported an error. Access denied. Cannot obtain the require interface ("IID_IDBSchemaRowset") from OLE DB provider "PGNP" for linked server "SHADOWDB".

MSSQL 2005
Postgres 8.3

Hope someone can help. Also, what is the difference between Developer and Business license - I am a developer and need to JOIN against a few tables in one Postgres database occasionally and a linked server would certainly make it easy.

FWIW, when I run the following query:

select * from openquery(SHADOWDB, 'select * from meta_bgnumberblock');

I get a different error:

Msg 7399, Level 16, State 1, Line 1
The OLE DB provider "PGNP" for linked server "SHADOWDB" reported an error. Access denied.
Msg 7350, Level 16, State 2, Line 1
Cannot get the column information from OLE DB provider "PGNP" for linked server "SHADOWDB".